Police are investigating a claim that a journalist who resigned from the Daily Star has become the victim of harassment.

Richard Peppiatt resigned in protest at what he alleged was the newspaper's anti-Muslim "hatemongering". His resignation letter, in which he confessed to making up stories during his two years at the tabloid, received widespread attention after it was disseminated via Twitter.

Peppiatt contacted police on Monday after he claimed to have received more than 30 abusive texts, emails and silent calls. He alleges they included warnings such as: "I am going to meet u now, pepps" and "you're nowe a marked man till the day you die – Oh dear". Another said: "we are planning a kiss n' tell on you".

Detectives are reviewing the messages and seeking to establish their origin. Peppiatt told them there is circumstantial evidence that a "likely source" may be connected to the Daily Star newsroom, although he concedes there is no firm evidence. He also expressed concern to them that his phone may have been hacked.

A spokesperson from the management of Northern & Shell, which owns the Daily Star, said he had asked several staff who had been in a position of authority over Peppiatt whether they were aware of the messages having been sent. "Every single one of them not only categorically denied it but evinced great surprise that the allegation had been made," the spokesperson said. "The same applies to any allegation of phone-hacking. We don't do that. It simply isn't done at the Daily Star."

News of the resignation of Peppiatt – who insists he has no knowledge of the source of the emails and texts – was published in the Guardian at 8pm on Friday. Hours earlier, Peppiatt says, he began to receive texts and emails from a tormenter using aliases such as "Micheala". The author knew he intended to go public with his grievances against the newspaper.

"Rich. It will tank. Maybe the best slot for you? Lots of love," said the first email, sent at 9.44am on Friday. Shortly after, another said: "Stop the bullshit, Pepps. We all know everything about you."

Later in the day Peppiatt says he began receiving texts demanding a meeting and referring to the London suburb where he lives.

Texts and emails named the Guardian reporter that Peppiatt had contacted. "Paul Lewis seems to know a lot about you, Pepps. You're far too trusting," said one. Peppiatt told police that Daily Star colleagues sometimes called him "Pepps".

The messages made references to a sitcom script Peppiatt was working on with friends in his spare time. Peppiatt had used his Daily Star email address to discuss the script about life in a tabloid newsroom and talked about the possibility of pitching the script, which is still incomplete, to a TV channel.

Managers at the Daily Star have been aware of his scriptwriting for some time, but found those emails after he resigned. Peppiatt's tormenter sent messages such as "U will NEVER see ur stuff on TV" and – in reference to one of the characters – "Please rewrite the Jack role. It's shit."

Peppiatt has told police he was concerned about the possibility his voicemail messages were listened to by the author of the anonymous messages. "Change ur VM message U sound like ur still at school," one email said, hinting this was the case.

Peppiatt said two voicemail messages temporarily went missing and were then referred to in the anonymous messages.

One was left by a Guardian reporter, but Peppiatt did not receive the message for more than 12 hours. During that time he received an email stating: "Paul Lewis has a message 4u."

The final message sent to Peppiatt, on Monday, also appears to refer to a lost voicemail. The message, which was left by a friend apologising because he could not join him for a football match, appears to have gone missing, Peppiatt said. He has still not heard it.

But the final voicemail made what Peppiatt believes may have been a reference to the contents of lost voicemail. "Sorry but cannot watch the football tomorrow night. I'll get back to you. PS This was my own decision, nut job. Adieu."

A Metropolitan police spokesperson said: "We can confirm that detectives are investigating an allegation of harassment received from a 26 year old man on 7 March 2011.